Buildings and Yards. 



547 



ventilation may be modified to suit different conditions of weather. When 

 dampers are used to cover these openings, allowance should be made 

 therefor. In many barns the openings are so reduced by the metal of the 

 dampers as to make them entirely inadequate. 



There is a popular fallacy 

 that the opening for the outlet 

 of vitiated air should be at the 

 bottom, on the theory that the 

 carbonic acid gas is heavier 

 than the air and sinks to the 

 floor. While it is true that 

 cold carbonic acid gas in a 

 perfectly still atmosphere will 

 fall on account of its greater 

 specific gravity as compared 

 with air of the same tem- 

 perature, it is likewise true 

 that the carbonic acid gas ex- 

 haled from animals or pro- 

 duced bv a lighted candle 

 promptly goes to the top of 

 the room. This is easily 

 demonstrated, but any one 

 who has occupied the gallery 

 of an audience room hardly needs to be told where the vitiated air is to 

 be found. 



It is obvious from what has been said that the eft'ectiveness of any 

 system of ventilation when applied to a cow stable will depend largely on 

 the rate at which the wind is blowing and on the exposure of the building 

 to the wind. It is desirable that the intakes for air should have a vertical 

 rather than a horizontal direction in order that advantage may be taken 

 of the force of the wind ; and since the wind may blow from all directions 

 it is desirable to have intakes on all sides of the building. In general, it 

 may be said that a number of small intakes and few large outlets will give 

 the best results. 



The most that can be hoped to accomplish in ventilating a stable is 

 to take the air out rapidly enough to maintain a dry atmosphere and not 

 so fast as to lower the temperature unduly. When the wind is blowing 

 and the weather cold, the best results will be secured by taking the air 

 out near the bottom of the room ; but when the atmosphere is warm and 



cu- 



FiG. 325. — Windows arranged to alloiv air to 

 t'sr with least amount of draft. Draiuings on 

 the left represent old ivindoivs modified by 



nailing on the 2x6 as indicated. 



